Tivo Bolt -- Receiving V52 "no signal" message on all channels

We have a Tivo Bolt that has worked fine for 4 years. Then, last week, suddenly ALL our channels went black...we're getting a V52 error code message on all of them. The Tivo interface works fine; we get our channel guide data through our internet, which we receive from a separate provider. I can see the entire guide and navigate fine...the channel signal itself isn't coming through.

I spent time on customer service calls and went through all the regular suggestions...restarting Tivo and checking connections on my end, while xfinity sent signals and restarted my service on their end. Nothing worked. They suggested I try getting a replacement CableCARD from my local store and replacing it. I did, called in to pair the new CableCARD, and still there was no signal. Black screens everywhere.

Got back in touch with Xfinity, and they sent out a tech. He checked our line and said it needed to be updated...that the signal was really bad. So, he fixed the problem and tested both the outside signal strength and the signal strength coming thought the Tivo line, and said everything looked good. Then, when he went to check for channels, we saw the same black screen. He called his supervisor, called his CableCARD people to re-pair it, and elevated the issue to his manager. Still no luck. He wasn't knowledgeable when it came to Tivos, and suggested I call Tivo support and ask them.

I'm doubtful this is a Tivo thing. It worked perfectly for 4 years and we can still access everything in the Tivo interface...we're just not receiving channel signals. I've read about other Xfinity subscribers gaining access to tier 3 support...I'd like to elevate my issue to that to check my account for any errors, but don't want to go through the lower tiers because I've spent enough time on this.

Any Xfinity support techs who can help me? I'm happy to provide any information I need to. Anybody else have any suggestions?